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中学数学中的非负数散见于各年级的教材,渗透于各门学科。由于具有非负数的条件,根据字母的不同取值,可以将式子化简,由于变形成非负数的形式,可以解某些方程,可以确定函数值的范围,可以证明某些不等式,几何中的“坐标”,“距离”等等,常取非负数。在解某些轨迹问题时,也可用到非负数。因此必须重视非负数的教学。中学数学中常见的非负数主要出现在下面一些情形: 1. 绝对值; 2. 算术根; 3. 一个实数的平方; 4. 三角形两边之和大于第三边; 5. 三角形内角的正弦值; 6. 当a≥1时,a±sinx,a±cosx的值;
Non-negative numbers in middle school mathematics are scattered throughout the grades of teaching materials and permeate various disciplines. Due to the condition of non-negative numbers, according to the different values of the letters, the expressions can be simplified. Since the forms of non-negative numbers are transformed, some equations can be solved, the range of function values can be determined, and some inequalities can be proved. The “coordinates”, “distance” and so on, often take non-negative numbers. Non-negative numbers can also be used when solving certain trajectory problems. Therefore, we must pay attention to non-negative teaching. The common non-negative numbers in middle school mathematics mainly appear in the following situations: 1. Absolute values; 2. Arithmetic roots; 3. The square of a real number; 4. The sum of the sides of a triangle is greater than the third side; 5. The sine of the inner angle of a triangle; 6. When a≥1, the value of a±sinx,a±cosx;